1. Field of the Invention
The present invention relates to a vehicle controller, and more particularly to a vehicle controller which performs overheat detection on a braking resistor when performing rheostatic braking control of an electric vehicle such as a railroad car.
2. Description of the Related Art
Up to now, a conventional vehicle controller uses power converting means to convert rotational energy of a motor into DC power at the time of braking control, and uses a braking resistor to consume the power as Joule heat (see, for example, JP 11-215605 A (page 4 and FIG. 1)).
The conventional vehicle controller has a problem in that when the Joule heat generated from power consumption at the braking resistor has become excessive, a temperature of the braking resistor also becomes high, resulting in burnout or smoking of the braking resistor.
In view of this, it is desirable to allow overheat detection on the braking resistor. However, for the purpose of the overheat detection, a temperature sensor needs to be provided in order to measure the temperature of the braking resistor, causing another problem in that the vehicle controller becomes expensive.